TW202226230A - Method to mute and unmute a microphone signal - Google Patents

Abstract

A method for muting and unmuting a microphone is provided. The method includes providing a processor, receiving an input microphone signal, measuring the input microphone signal for a loudness level at a sampling rate, calculating a mute threshold level, checking if the loudness level is higher than or equal to the mute threshold level, and resetting a mute delay timer upon determining that the loudness level is higher than or equal to the mute threshold level and obtaining the input microphone signal, or checking if the mute delay timer is running upon determining that the loudness level is not higher than or equal to the mute threshold level and attenuating the input microphone signal if the mute delay timer is not running or obtaining the input microphone signal if the mute delay timer is still running, and writing the input microphone signal or attenuated input microphone signal to an output buffer.

Description

How to mute and unmute the microphone signal

The present invention generally relates to muting and unmuting of microphone signals, and more particularly to muting and unmuting of microphone signals using voice activity detectors.

Microphones are used during voice or video calls such as telephone calls or Internet calls (with or without video, which utilize communication software such as Zoom, Skype and Microsoft Teams). Typically, the microphone is always enabled during the call. However, always-enabled microphones can pick up unwanted background noise or unintentional audio from the environment, which results in interference and impact on the far-end party in the call. To avoid this problem, typically during the call, the user will mute his microphone when he is not speaking, so the background sound/noise will not be heard by the other far-end parties in the call. The microphone can also be preset to mute in order to minimize disruption to other users. But users may often forget to unmute the microphone when they start speaking.

Thus, it can be seen that what is needed is a method to mute and unmute the microphone signal when the user is not speaking and when the user is speaking, respectively. Furthermore, other desirable features and characteristics will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and this background of the disclosure.

In one feature of the present invention, a method for muting and unmuting a microphone is provided. The method includes setting a processor, receiving an input microphone signal, measuring a volume level of the input microphone signal at a sampling rate, calculating a mute threshold, and checking whether the volume level is above or equal to the mute threshold level, and after judging that the volume level is higher than or equal to the mute threshold level, reset a mute delay timer and obtain the input microphone signal, or determine the volume level Check if the mute delay timer is running after the mute threshold level is not above or equal to the mute threshold level, and if the mute delay timer is not running, attenuate the input microphone signal, or if the mute delay timer is not running With the mute delay timer still running, the input microphone signal is obtained and either the input microphone signal or the attenuated input microphone signal is written to an output buffer.

In another feature of the present invention, a software product is provided that includes a non-transitory storage medium readable by a processor, the non-transitory storage medium having stored thereon a set of instructions for Mute and unmute an input microphone signal. The software product includes a first sequence of instructions that, when executed by the processor, cause the processor to receive an input microphone signal, a second sequence of instructions, when executed by the processor , which causes the processor to measure a volume level of the input microphone signal at a sampling rate, a third sequence of instructions that, when executed by the processor, cause the processor to calculate a Mute critical level, a fourth sequence of instructions that, when executed by the processor, cause the processor to check whether the volume level is higher than or equal to the mute critical level, and when judging the After the volume level is higher than or equal to the mute threshold, reset a mute delay timer and obtain the input microphone signal, or determine that the volume level is not higher than or equal to the mute threshold Check if the mute delay timer is running after calibration and attenuate the input microphone signal if the mute delay timer is not running, or get the mute delay timer if the mute delay timer is still running The input microphone signal, and a fifth sequence of instructions, when executed by the processor, cause the processor to write the input microphone signal or the attenuated input microphone signal to an output buffer.

The following detailed description is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. Furthermore, there is no intention to be bound by any theory presented in the preceding background of the invention or the following detailed description. One of the intent of the various embodiments is to present a method of muting and unmuting a microphone signal.

Referring to FIG. 1, a flowchart 100 depicting a method for muting and unmuting a microphone signal in accordance with various embodiments is shown. A device is provided with a processor. The processor receives an input microphone signal in step 110 , and the volume level of the microphone signal is measured in step 120 . In an embodiment, the input microphone signal may be in the frequency domain. The frequency band amplitude of the microphone signal from a frequency band can be measured by taking the root mean square (RMS) of the complex input microphone signal and multiplying it by an amplitude scaling factor. The frequency band may be from a lower frequency (eg, 250 Hz) to an upper frequency (eg, the Nyquist frequency of the input microphone signal or 8000 Hz, whichever is lower). The amplitude scaling factor takes into account the sampling rate of the audio. In one embodiment, the amplitude scaling factor may be the inverse of the square root of a function of the sampling rate and frame size. By multiplying by the amplitude scaling factor, the frequency band amplitude becomes constant for different sampling rates and frame sizes.

The current volume level is obtained by smoothing the frequency band amplitude using a smoothing function with a rise response time and a release response time. The rise response is how quickly/slowly the smoothed value will increase compared to its previous value, and the release response is how quickly/slowly the smoothed value will decrease compared to its previous value. In one embodiment, the rise response time and release response time are 16 msec. The volume level of the microphone signal is measured in real time, with a sampling rate of 16kHz, a sound frame size of 512, a rise response time of 16msec, and a release response time of 16msec, so that the volume level of the microphone signal can be adjusted every time. 32msec was judged. As will be described in further detail below, this advantageously will allow the microphone signal to be unmuted almost immediately without loss of speech. Depending on system resources and constraints, other suitable sample rates and sound frame sizes may also be utilized. For example, a sampling rate of 48 kHz and a sound frame size of 512 allow the volume level of the microphone signal to be determined every 10.67 msec.

In step 130, the processor calculates a mute threshold according to the voice activity detection (VAD) setting. In one embodiment, the mute threshold level is set according to one of five different VAD modes. The modes are automatic calibration, manual calibration by default, manual calibration by default levels, manual calibration by custom values, and real-time auto-adjustment. In one embodiment, the preset preferred mode is the instant auto-adjustment mode.

When the mode is set to automatic calibration, the user is required to remain silent for a certain duration (eg, at least 3 seconds) while audio calibration is in progress. During auto-calibration, the processor measures the peak ambient noise level and adjusts the mute threshold level according to the measured level. The peak noise can be measured for every 200ms of the microphone signal and stored in a circular buffer of size 8. This is the same as for the peak noise for the last 1.6sec (8x200ms) acquisition, which is updated every 200ms. A button can be made available to the user to initiate the calibration. Although automatic calibration can give more accurate measurements of ambient sound/noise levels, it requires the user to perform this calibration at the beginning of each call.

When the mode is set to pass a preset manual calibration, the user is asked to take into account their speech level (eg loud, moderate, soft), ambient noise level (eg high, moderate or low background noise) , and the microphone in use (eg headset, earbud, forehead, far-field) to select different presets. The mute threshold level is set according to a pre-defined preset value that is locally pre-tuned to correspond to the selected preset.

When the mode is set to manual calibration via preset levels, the user is asked to select a custom preset, such as but not limited to a specific microphone type and model and environment type. For example, the user may be presented with microphone options such as "Creative Labs Live! Cam Sync HD 1080p Webcam Microphone", "Lewitt LCT 640 TS Microphone", "Audio Technica AE2300 Microphone", "Panasonic Dynamic Microphone WM-530", etc. Wait. The user may also be presented with environment options, such as "market", "shopping mall", "office", and the like. The mute threshold level is set according to the preset level corresponding to the selected customized preset.

When the mode is set to manual calibration with custom values, the mute threshold is set based on a noise floor and a user-defined fixed offset. A slider may be presented to the user to allow the user to adjust the offset value for the VAD. The noise floor can be measured by tracking the minimum level of the frequency band amplitude using a smoothing function with a slow rise response and a fast release response. The rise response is the response of how fast/slowly the smoothed value will increase compared to its previous value, and the release response is the response of how fast/slowly the smoothed value will decrease compared to its previous value. In a preferred embodiment, the rise response time is 10sec and the release response time is 50msec.

When the mode is set to auto-adjust on-the-fly, the mute threshold level continues to be updated on-the-fly. During mute conditions, the mute threshold level is based on transient peak noise. In a preferred embodiment, smoothing is applied with a rise response time of 1 msec and a release response time of 2000 msec. The peak noise is measured for each 200ms microphone signal and stored in a circular buffer of size 8. This is the same as for the peak noise for the last 1.6sec (8x200ms) acquisition, which is updated every 200ms. During the mute to unmute transition, the previous mute threshold level value may be stored as a mute threshold (minimum) value. During an unmute-to-mute transition, the circular buffer is cleared. During unmuted conditions, the mute threshold level is based on the average volume level. In a preferred embodiment, the average volume level is calculated by smoothing the measured band amplitudes with a rise response time of 200msec and a release response time of 200msec. If the calculated average volume level plus a predefined fixed offset is lower than the stored mute threshold (min) value, the mute threshold (min) value will be used. In a preferred embodiment, smoothing is applied with a rise response time of 2000 msec and a release response time of 2000 msec. Advantageously, there are no configuration settings for the user to set or select in the auto-tuning mode.

In step 140, the processor checks whether the volume level is greater than or equal to the mute threshold level. When the check indicates that the volume level is greater than or equal to the mute threshold level, the mute delay timer is reset in step 150 . The mute delay timer controls when the microphone will be automatically muted (by attenuating the microphone signal) when the measured volume level is below the mute threshold. The mute delay timer is reset in step 150 whenever the measured volume level is higher than or equal to the mute threshold level. When the measured volume level is lower than the mute threshold level, the mute delay timer will continue to run in step 180 until the timer expires. When the timer expires, the input microphone signal will be sufficiently attenuated in step 190 to achieve the effect of muting the microphone. The mute delay timer setting is applicable to all five modes, and the user will be able to set a preferred value. In one embodiment, the preset value is 1 second. A mute delay of 1 second means that if no voice activity is detected for 1 second, the microphone will be muted. The mute delay timer advantageously allows reducing unnecessary brief mute of the microphone due to the user briefly pausing his speech during a call, which greatly enhances the overall experience of the call. The raw microphone signal is obtained in step 160 and written to an output buffer in step 170 before returning to step 110 . The effect of unmuting the microphone signal is achieved when the original microphone signal is written to the output buffer. The effect of muting the microphone signal is achieved when the microphone signal is attenuated in step 190 and written to the output buffer in step 170 .

On the other hand, when the volume level is not greater than or equal to the mute threshold in step 140, the processor will check in step 180 whether the mute delay timer is running. When the check indicates that the mute delay timer is running, the routine proceeds to step 160 followed by step 170 . On the other hand, when the mute delay timer is not running (timed out), the microphone is muted in step 190 by attenuating the microphone signal, and the process returns to step 110 before returning to Advance to step 170 first. The method in flowchart 100 continuously measures the input microphone signal.

In one embodiment, a visual indicator is displayed to the user of the current mute status. As the user selects and adjusts their VAD settings, the microphone signal is simultaneously analyzed and the mute status is displayed so that the user can make changes to the VAD settings accordingly. Since the environmental conditions when the user previously selected and adjusted their VAD settings may be different from the actual environmental conditions during the actual call, displaying the current mute status for the entire duration of the call allows the user to know the instant mute status and, if necessary, If so, the user can make changes to the VAD settings accordingly.

During silent conditions, the microphone signal is attenuated to have a microphone-like muting effect. In a preferred embodiment, dynamic attenuation techniques are implemented that take into account the strength of the instantaneous microphone signal, rather than applying a fixed attenuation to mute the microphone signal. When the user is not speaking and the microphone signal level is low (eg in scenarios where background noise is therefore low), less attenuation will be applied to achieve the target mute audio level of the microphone signal . When the user is not speaking and the microphone signal level is high (eg in scenarios where the background noise level is therefore high), more attenuation will be applied to achieve the target mute audio level of the microphone signal . The target mute audio level for the microphone signal is determined so that the level is low enough that no one can hear the audio, but high enough that the communication application can still detect the presence of the attenuated microphone signal. The attenuation level is calculated according to the target audio level (eg, about -66dB) of the input microphone signal during a silent condition and the currently measured volume level, wherein the smoothing utilizes a rise response time of 2000msec and a 200msec release response time is applied. Advantageously, this prevents some communication applications from thinking that there may be a problem with the user's microphone or audio system settings due to their inability to detect the presence of a microphone signal during communication.

Although the steps in the flowcharts are presented sequentially, it should be recognized that certain steps may be performed concurrently, or in different sequences. The steps can be implemented in hardware, software, firmware, or any combination thereof.

Thus, it can be seen that a method has been proposed to mute and unmute the microphone signal when the user is not speaking and when the user is speaking, respectively. One advantage of the present invention is that it provides a way for the device to automatically mute and unmute the microphone when the user is not speaking and when the user is speaking, respectively. Advantageously, the microphone is unmuted almost immediately without loss of speech.

While example embodiments have been presented in the foregoing detailed description of this embodiment, it should be appreciated that a vast number of variations exist. It should be further appreciated that the exemplary embodiments described are examples only, and are therefore not intended to limit the scope, applicability, operation, or configuration of the invention in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient plan for implementing exemplary embodiments of the present invention, with the understanding that various modifications may be made to the steps and methods of operation described in the exemplary embodiments in function and Arrangements are achieved without departing from the scope of the present invention as set forth in the appended claims.

100: Flowchart 110: Steps 120: Steps 130: Steps 140: Steps 150: Steps 160: Steps 170: Steps 180: Steps 190: Steps

[FIG. 1] is a flowchart depicting a method for muting and unmuting a microphone signal according to various embodiments.

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Claims (20)

A method for muting and unmuting a microphone signal, comprising: set the processor; Receive input microphone signal; measuring the volume level of the input microphone signal with a sampling rate; Calculate the mute critical level; Check whether the volume level is higher than or equal to the mute threshold level, and reset the mute delay timer and obtain the input microphone signal after judging that the volume level is higher than or equal to the mute threshold level , or check whether the mute delay timer is running after judging that the volume level is not higher than or equal to the mute threshold level, and if the mute delay timer is not running, attenuate the mute delay timer an input microphone signal, or if the mute delay timer is still running, obtaining the input microphone signal; and The input microphone signal or the attenuated input microphone signal is written to an output buffer. The method of claim 1, wherein the input microphone signal is in the frequency domain, and the step of measuring the volume level of the input microphone signal is by taking the root mean square of the input microphone signal and multiplying it by an amplitude scaling factor. The method of claim 2, wherein the amplitude scaling factor is the inverse of the square root of a function of the sample rate and frame size. The method of claim 1, wherein the volume level of the input microphone signal is determined every 32 milliseconds. The method of claim 1, wherein the step of calculating the silence threshold includes examining a voice activity detection mode, and obtaining a set of parameters for calculating the silence threshold. The method of claim 5, wherein the voice activity detection mode consists of automatic calibration, manual calibration through presets, manual calibration through preset levels, manual calibration through custom values, and real-time automatic adjustment is selected from the group of , and wherein the instant auto-adjustment mode is selected by default. The method of claim 1, wherein the silence delay timer is configured to be 1 second. The method of claim 1, further comprising the steps of obtaining a preferred value for the silence delay timer for a user, and configuring the silence delay timer to the preferred value. The method of claim 1, further comprising the step of displaying a visual indicator to show the current mute state. The method of claim 1, wherein the step of attenuating the input microphone signal comprises determining an attenuation value based on a target audio level of the input microphone signal and the volume level, and wherein the target of the input microphone signal The audio level is low enough that a human cannot hear the audio, but high enough that the communication application still detects the presence of the attenuated input microphone signal. A software product comprising a non-transitory storage medium read by a processor, the non-transitory storage medium having stored thereon a set of instructions for muting and unmuting an input microphone signal, comprising: a first sequence of instructions that, when executed by the processor, cause the processor to receive an input microphone signal; a second sequence of instructions that, when executed by the processor, cause the processor to measure the volume level of the input microphone signal at a sampling rate; a third sequence of instructions that, when executed by the processor, cause the processor to calculate a mute threshold level; A fourth sequence of instructions, when executed by the processor, causes the processor to check whether the volume level is higher than or equal to the mute threshold, and to determine that the volume level is higher than Either reset the mute delay timer and obtain the input microphone signal after equal to the mute threshold level, or check the mute delay after judging that the volume level is not higher than or equal to the mute threshold level whether a timer is running and attenuates the incoming microphone signal if the mute delay timer is not running, or obtains the incoming microphone signal if the mute delay timer is still running; and A fifth sequence of instructions, when executed by the processor, causes the processor to write the input microphone signal or the attenuated input microphone signal to an output buffer. The software product of claim 11, wherein the input microphone signal is in the frequency domain, and the volume level of the input microphone signal is quantified by taking the root mean square of the input microphone signal and multiplying it by an amplitude scaling factor Measurement. The software product of claim 12, wherein the amplitude scaling factor is the inverse of the square root of a function of the sampling rate and sound frame size. The software product of claim 11, wherein the volume level of the input microphone signal is determined every 32 milliseconds. The software product of claim 11, wherein the mute threshold level is calculated based on a voice activity detection mode and a set of parameters. The software product of claim 15, wherein the voice activity detection mode is selected from the group consisting of automatic calibration, manual calibration through presets, manual calibration through preset levels, manual calibration through custom values, and real-time automatic adjustment. is selected from the group consisting of, and wherein the instant auto-adjustment mode is selected by preset. The software product of claim 11, wherein the silence delay timer is configured to be 1 second. The software product of claim 11, further comprising a sequence of instructions that, when executed by the processor, cause the processor to obtain a preferred value for the silence delay timer for a user, and Configure the mute delay timer to the preferred value. The software product of claim 11, further comprising a sequence of instructions that, when executed by the processor, cause the processor to display a visual indicator to display a current mute state. The software product of claim 11, wherein the input microphone signal is attenuated by an attenuation value that is dependent on a target audio level of the input microphone signal and the volume level, and wherein the target of the input microphone signal The audio level is low enough that a human cannot hear the audio, but high enough that the communication application still detects the presence of the attenuated input microphone signal.

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